Electric hammer



Jani 20, 1948. B. w. sNoDGRAss ELEC TRI C HAMMER Filed March l, 1946 3Sheets-Sheet l l N V EN TOR.

rrams Y V A w Jam 20, 1948l B. WQ sNoDGRAss 2,434,725

ELECTRIC HAMMR Filed March l, 1946 3 Sheets-Sheet 2 l Jan. 20, 1948. B.w. sNoDGRAsS ELEC TR I C HAMMER Filed March l, 1946 3 Sheets-Sheet 3 I NV EN TOR. 5 NJA/WN h( /voeqss Troef/Ey Patented Jan. 20, 1948 BenjaminW. Snodgrass, nver,f(lolo, ssiigiiioi' of one-half to Benjamin F.Englandr'nver,

Colo.

Appiicsfiofi March 1, 194e,seriiiibftsin e claims. (ci. ess-e6) Thisin`vention relates to powered hammer devices adapted to Ageneraterapidly successive impacts applicable Afor work eiect and t'o directysaid impacts to the effective actuation of drills,vchisels, tamps, andanalogous tools susceptible of interchangeable association therewith,and more particularlyto electrically-driven such hammer devices, and hasas an object to provide an improved constructionanvd cooperativearrangement of elenifentfs constituting 'an improved hammer of highei'ciency and "wide utility.

AT further `object of the inventionv is to provide animprovedconstrl'iction and'operative mounting for a reciprocatory impactmember in an electrically-driven hammer. 1 ,n

A furtherfobject oi the invention is to provide jimprovedimpactgtrans'mitting tool mounting in 'an electrically-driven hammer.

` AA further object `of the invention is to provide an improvedconstruction and arrangement of rnea'n's automatically operable as anincident of 'ipaot ii'iehlb'er aotton to rotate the tool mountingandgassociated tool of an electricallydriven hammer. A

A `fu-rtherobjeot of the invention is to provide an improvedconstruction and arrangement of means automatically eiective as anincident of hammer "actuation to pressure feed liquid to and 'throughthelwork 'end of a t'ol associated 'with an eiec'tncaiiy-drivenliiaiiiiiiei.

A further object of the invention is to provide {iniproved operativedriving connections between "an impact member reciprooably responsive torotation 'and a powered shaft in a-Xial alignment with Asaid member. l yI With the foregoing and other objects in view, 'my invention consistsin the construction, arrangement, and combination of elementshereinafter s'etrforth, pointed out in my claims, and illustrated by theaccompanying drawings, in whch- V g, Figure lisa view, largely inlongitudinal, axial section, of a typical embodiment of the invention'as assembled ready for 'practicall use` Figure 2 an exterior elevationof the assembly according to Figure l takenat arright angle and on areduced Scale rfr'elativeto said latter figure. Fi`gure 3 is afragmentary, detail, axial section, on rxan enlarged scale, through toolmounting and 'actuating elements of the assembly according to ajndsubstantiallyon the indicated line 3 3 of Figure 1 depicting 4saidelements on a plane 15erpendicular to thelshowingwof said latter 'gureand jatfan opposite 'extreme of their range of actuation. Figure 4 is across section, von the `'same "of the type s scale as rigie takenjgmrtiiexiniiicatee une lr-44 of Figure 1.A Fijgurefis acrosssection/pri the 'saine scale fais,y Figure 3,., taken Aon thein'dicate'dtiongon the same scale as Figure, taken on the indicated line Sri-6 ofFigure 1. Figure 'i kis a cross section, ,on the same scale as Figure 3,taken gouine iiiciiated iiiife 1+i of 4Figure 1. AFigure s A1944, and`are applicable to use with and to enh "ce the pra'cticability and`eilieienoy of electrically-driven ita'ower haiin'ers n 'in Asiilpatenti, particularly when suchh rnesar'e employed in the drilling ifrieles incident t -infiniiig 'and blasting opera- 'tiorfsr l As Shownrthe daw'igsfa cylindrical casing vitl 'opera'velyiii-nts, houses, andprotects the lfilature oidiven shaft "H Vis suitably jurled in 'ai'alcoincidence "with said casing. Fixed to and 'for 'rotation vwith one endof the shaft Il, disc-like drive ,iplat I2 is operatively housed'somewhat iiivvaiaiy from 'one end of the casing ijn @lowly-adjacent,independently-rotatable, hovering relation with thel axially andcylindri- "c'ally recessed end "of a clutch member I3 carried`'iit'e'riorly of said casing end for rotation about an airis 'alignedthat 'f the shaft ll`. The recess of the 'irnembe'r l`3covere`d by theplate I2 cojo ratively receives fa pairof complementary, semi-circm i4having' manica-lagged, rouate outer margins f5 adapted to 'Conform tOand engage at times' against the inner cylindrical wail 'f the ksaidreces-s, and pins it nxediy projec'ting 'a-iial y fron'i the 'outer"face of the plate il. are received tangentially-elongate slots l1formed in and adjacent the ends of said shoes 'to engage the vlatter'inconstantdriven relation fvith said plate y"and shaft Il in a mannerpermitti g ofv'siepartion and 'iappro'chment of "the shoeelementsaiaiiieiificaiiy bf jsid plate within said u e coil springs T8of suitable tensile resi e `'oper tively engage between inn margins dftrie Sintes r4 and iena to honi said shoes in end abutment the innerlimit of their geiilsepar'at out of margin len'gage- Ynt the Inbe'r `i`3recess inner cylindrical wail; iii which@ @utp saidnshqe's are free torptft I2 interfi'orly of and Without driving 'eiect on the vrecess andmember until such a speed of rotation is attained as will generatecentrifugal forces acting on the mass of said shoes suicient to induceoutward separation of the shoe elements such as will overcome thetension of the springs I8 and frictionally engage the shoe margins Iagainst the recess wall and in driving relation with the member I3.Wedge blocks I9, having each an outwardly-directed point disposed forWedging engagement between abutted ends of the shoe I4 elements, areasso- 'ciated with and interiorly of said shoes for limited travelradially of the assembly and for outward shifting in response tospeed-generated centrifugal forces, said blocks I9 functioning in anobvious manner to enhance and maintain the frictional grip of themargins I5 against the member I3 recess wall, at proper rotative speeds,and to thereby minimize vagrant fluctuations in the soestablishedfrictional driving relation. The speed-responsive clutch just describedis functionally identical With and structurally very similar to thatshown in myearlier patent and in and of itself forms no part of theinstant invention, being herein illustrated and described merely tofacilitate understanding of the structural and operative relationshipsof a complete hammer assembly.

The clutch member I3 is formed with a transverse web closing the end ofits shoe-containing recess remote from the plate I2 and an annularflange outstanding axially from said web to define a cylindrical cupconcentric with the plate I2 and opening outwardly of the casing I9therefrom; said annular ange projecting axially beyond the adjacent endof the casing I3 for journaled reception within thecylindricallyrecessed end of a tubular casing member 23 xedlyend-engaged with and forming an axiallyaligned extension of said casingI0. The casing member 23 is axially traversed by a straight, cylindricalbore opening at one end into the cup defined by the member I3 annularflange and at its other end into a radially-enlarged, concentric,two-diameter, cylindrical chamber whereof the lesser portion is adjacentand communicates through an abrupt angular shoulder 2I with said boreand the greater portion is adjacent and arranged to open outwardlythrough the casing member 20 end remote from the clutch member I3. Asuitably-worked, straight stern 22 is disposed axially of and to extendentirely through the straight bore portion of the casing member 20 inadjustable, interconnecting relation between a double-cone impact head23 housed within the two-diameter chamber at one end of said bore and adrive disc Ztl housed within the cylindrical cup of the clutch member I3at the other end of said bore, said stern, impact head, and drive discconstituting a unitary assembly rotatable and reciprocable relative tothe casing member 2B. Work-effecting reciprocation of the stem 22, head23, and disc 2li assembly is developed as a consequence of assemblypower rotation through the agency of a double-faced, suitably-contouredcam block 25 adjustably xed to an intermediate portion of the stem 22within the casing member 2D bore between and f or reaction againstindependently-rotatable cam followers 26 radially overhanging the block25 cam margins from their diametrically-oppose'd, axially-spaced, pairedmountings in the casing member 20 wall, in much the same manner and withthe same effect described in my earlier patent, and power to rotate saidassembly is transmitted thereto from the clutch member I3 4 through aplurality of posts 21 fixedly outstanding from the member I3 web inuniformly-spaced angular relation inwardly adjacent and axiallyparalleling the annular ilange surrounding the drive disc 211, whichposts register with and slidably engage through corresponding marginalnotches or apertures intersecting said disc 2li, thereby locking saiddrive disc to and for rotation with the clutch member in a manner toaccomvcycle determined by the lobe arrangement and contour of the blockcam faces; the illustrated construction being designed to eiect twocomplete reciprocatory cycles for each revolution of the stem 22 and tofree the reciprocatory assembly from every mechanical actuating force orrestraint at each limit of its reciprocatory travel, in the manner andfor the purposes set forth in my above-identiiied, previous patent.

The end of the casing member 20 remote from the casing I0 xedly engagesand cooperates with one end of a tubular sleeve 28 thereby mounted andsupported in axial alignment with and as an extension outwardly beyondsaid casing member end, said sleeve having a straight, axial bore of adiameter somewhat less than that of and communicating at its inner endwith the larger portion of the two-diameter chamber housing the impacthead 23, so that the sleeve 28 inner end serves to partially obstructand limit the axial length of said chamber. A tool mounting unit isformed with a straight, tubular end portion 29 of a length slightlygreater than that of the sleeve 28 and an external diameter engageableWithin the sleeve bore to rotatably and reciprocably mount said portion29 within and through said sleeve with its inner end projecting into thegreater portion of the two-diameter chamber for engagement at times bythe impact head 23. An annular, radially-outstanding collar 33 formedintegrally about a midportion of the tool mounting unit determines theexterior length of the tubular portion 29 and is t adapted to engage attimes against the outer end of the sleeve 28 and thereby limitprojection of said portion 29 inwardly beyond the adjacent sleeve end,and a cylindrical extension 3I of said unit axially and outwardly beyondthe said collar 3l] is formed with an end-opening, concentric,inwardly-tapered socket 32 separated `from the bore of the tubularportion 29 by a solid transverse web 33 and adapted to telescopicallyreceive, seat, and frictionally grip the correspondingly-tapered end ofa tool stock 34. The tool mounting unit is held against separation fromand limited in its range of reciprocation outwardlyof the sleeve 2li byan annulus 35 rotatably and reciprocably embracing the extension 3ladjacent the collar 30, said annulus being equipped with fixed,radially-outstanding ears 33 adapted to register with and end-abutagainst corresponding ears 31 fixedly carried by the sleeve '28 outerend and be clamped thereto by means of bolts 38 engaged throughregistered holes intersecting said ears in parallelism with thelongitudinal axis ofthe tool assembly, adjustment in the spacing betweenthe sleeve 28 outer end land the annulus 35, and hence in thereciprocatory range ofthe tool `mounting unit as determined -byengagemen-t of the collar Swithin such space, being conveniently had -ina usual manner through the use of shims or spacers between adjacent endsof the ears 36 and 31.

As should be manifest from the drawings and Yforegoing description,axial 4reciprocation of the stem `22 deriving from actuation of theshaft Il is reflected adjacent t-he limit of stem Vtravel re- -mote-fromthe casing 'l as impact engagement of the head 23 against the innerend of ^the tool mounting 'unit Atubular portion v2-9, and through `theelements of said tool mounting unit to and ifor -work effect through thestock 34 and tool associated therewith, weight or feed pressure of the-tool assembly applied 4to the stock 34 serving to normally vurge thetool mounting unit to vmaximum inward projection of its tubular portion29 yfor maintenance of said tubular portion in position for repetitiousimpact engagement by said head 23. Stem 22 travel Itoward. the casing Ill is arrested by engagement of the impact head inner cone base againstthe annular shoulder 2l, and the range of stem travel, normal positionof the -tool'mounting unit tubular portion inner end, land clearancesbetween cam surfaces of the lblock 25 and the followers '26, are socorrelated with other pertinent operative factors and with each other asto synchronously utilize rebound of the head Z3 and associated elementsfor initiation of travel in a direction adapted for smooth subsequentacceleration by means of the Lpowered associations iprovided.

Certain operations to Awhich the improved hammer is applicable arefacilitated and expedited by providing for rotation of the working tool,to -which end means and operative associations effective for suchpurpose are `incorporated in and with the elements hereinabovedescribed. The tool mounting unit of the improvement being rotatably, aswell as reciprocably, carried by the sleeve 28 and annulus 35, andarranged for frictional, rotation-imparting grip with the associated endof the tool stock 34, it is convenient and wholly feasible to apply thepowered rotation of the stem 22 and head `23 to eifect tool mountingunit rotation in a practical manner free from disastrous consequencesoccasioned by sticking tools. As shown, a pair of complementary,semi-cylindrical shoes 39, of suitable rigid material, have theirexterior, cylindrical "surfaces suitably friction-lagged, as at 40, andare sized to slip axially within and cooperate to substantially ll thebore in the tubular portion 29 of the tool mounting unit; the lengths ofsaid shoes 39 being slightly less than that of the tubular portion bore,so as to clear said shoe ends from any possible driving engagement withthe impact head 23. The plane, diametric faces of the shoes 39interengageable to complete a shoe cylinder housable within the tubularportion 29 are centrally and longitudinally grooved or routed to form-corresponding transversely-arcuate, relatively wide, shallow channelscooperable when the said shoes .are assembled as shown to denne atransverselyoval bore extending axially of and entirely through thecylinder comprised from the shoes; the so-iormed oval bore being adaptedto t snugly about and :slidably accommodate a similarlytransversely-oval tongue 4l xedly projecting axially and outwardly fromthe impact head 23 a distance slightly less than the axial depth of the6 tubular yportion bore. With the arrangement of elements shown anddescribed, rotation-induced reciprocation-ofthe impact membercarryingthe head 23 is reflected without impairment or restriction by acorresponding axial play of the tongue 4l longitudinally vwithinandbetween the shoes 39'; the powered rotation of said impact Vmemberoperating, -by virtue of -the interengaged tongue and shoe borecross-sectional outlines, to rotate the shoe assembly and tosimultaneously :urge said shoes radially apart and linto 4suchfrictional `engagement of their 'lagged surfaces :against the tubularportion 29 inner Wall as will rotate the tool mounting and the tooltherewith associated. 'While the centrifugal forces of rota-Iencountered by the tool may instantly be accommodated through slippagebetween the shoe `surfaces 49 and tubular portion 29 without unduestrain on, damage to, or interruption in the operation of the hammerassembly elements.

In rock, coal, concrete, and like drilling operations to which theimproved hammer is effectively applicable, it is a highly desirablecommon practice to continuously supply liquid, such as Water,

to the working face of the drill for cooling -eifect on the latter andto free the working area of dust and chips which `impair drillingeiciency, it being usualand convenient to form the tool stock 34 with anaxial bore or channel 42 wherethrough such liquid-may Vbe fed to andoutwardly from the tool Working end, and a further novelty of theinstant invention resides in the provision of means automaticallyoperable .as an incident of hammer actuation to pressure-supply liquidto and through the tool stock. Conveniently adapting the improved hammerfor liquid supply to the tool actuated thereby, the driven shaft ll ofthe hammer motor is extended, through suitable packing glands (notshown), axially and outwardly beyond its'supporting bearing remote fromthe drive plate `l2 and 'into an end-opening compartment formed in thecasing l0 free end, where said shaft engages in driving relation with agear 43, rotatably housed in said compartment. Radially--offset from andin-meshing relation with the gear 43, a second gear 44 is housed andmounted for rotation about its axis within said casing end compartment,and the inner walls of said compartment are formed and contoured toprovide chambers on each side of the diametric plane containing the axesof the gears 43 and 44 and inwardly-extending abutments closelycooperating with the outer opposite arcs of said gears in separatingrelation between said chambers. A cap 45 removably and replaceablycooperates with the free end of the casing l0 to operatively confine thegears 43 and 44 and to complete the chambers oppositely adjacentthereto, said cap being apertured to provide access to the casingchambers covered thereby and supporting iiow lines 46 and 41communicating through the cap apertures and with the respective chamberinteriors. The meshed gears 43 and 44 constitute a pump operable to drawliquid through one of the flow lines and into the chamber servedthereby, to transfer the incoming liquid from the inow chamber to theother chamber of the casing compartment, and to deliver the liquid underpressure as outflow through the other of the flow lines, according tothe direction of gear rotation, the line 46 in Figure 1 accommodatingliquid inflow and the line 41 functioning as a conduit for pressureoutflow when the gear 43 of Figure 6 is rotated in a clockwisedirection. The gear pump being productive of operatively adequatesuction eifect, the inow line 45 may connect with any convenient sourceor supply of liquid, such as a sump, tank, reservoir, or the like, andneed not be pressure served. The pressure outiiow line 41, which may beeither a flexible conduit or a rigid pipe assembly, is led exteriorly ofand along the hammer assembly to connection of its delivery end with andradially through the annulus 35, said latter element advantageouslybeing formed with an annular groove 48 shallowly intersecting its innerface and arranged to receive and distribute liquid inflowcircumferentially about the adjacent exterior area of the tool mountingextension 3|, and with annular marginal shoulders cooperating withcomplementary elements on the collar 30 and extension 3l to minimizeliquid leakage therebetween. A plurality of flow channels 49 is formedradially of the extension 3| in communicating relation between the innerend of the socket 32 and the outer surface portion of said extensionunderlying the groove 48, so that the flow delivered to said groove fromthe line 41 may freely enter the inner socket end and the bore 42 of thetool stock 34 engaged in said socket and be thence pressure-impelledthrough and outwardly of the tool working face. Thus, actuation of thehammer power unit may be directly and automatically applied to maintaina liquid iiow to and through the tool actuated thereby, whenever andwherever liquid serving of the tool is desired.

The improved hammer assembly may be equipped with manipulating andoperating handles and switch in such speciiic construction andarrangement as may be deemed to be practical, such features beingconventional in association with hammers of the type disclosed herein,and suitable lugs and brackets for operative engagement with manual orpowered feeding mechanisms and supports may be provided in fixedrelation with the casing l!) and casing member 2i), as is customary inthe application of powered hammers to particular uses.

Since many changes, variations, and modifications in the specific form,construction, and arrangement of the elements shown and described may behad without departing from the spirit of my invention, I wish to beunderstood as being limited solely by the scope of the appended claims,rather than by any details of the illustrative showing and foregoingdescription.

I claim as my invention:

1. In an electric hammer of the character described having a tubularcasing assembly, an electric motor housed in one end and with its powershaft axially of said assembly, and a speedresponsive clutch including ashaft-concentric driven member `operatively associated with the motorpower shaft inner end interiorly of said assembly, a tool mounting unitrotatably and reciprocably carried in the end of said assembly remotefrom said motor, an impact member rotatable and reciprocable axiallywithin said assembly between said clutch driven member and tool mountingunit, an axially-slidable, angularly-fixed, rotational drivingconnection be.. tween said clutch driven member and one end of saidimpact member, a head on the other end of said impact member forrepetitious work-effecting engagement against the tool mounting unitadjacent end, cooperating impact member cam and casing assembly followermeans eifective to reciprocate said impact member as an incident of itsrotation, a tongue xedly projecting axially from said impact member headin slidably-supported association with said tool mounting unit, andmeans reactive to rotation of said tongue for frictional engagement withand consequent rotation of said tool mounting unit.

2. Apparatus as Set forth in claim 1, wherein the rotational drivingconnection between the clutch driven member and the impact membercomprises a plurality of studs iixedly projecting toward the adjacentimpact member end from, in axial parallelism with, and inangularlyspaced relation on said clutch driven-member, a disc radiallyof and xed to said impact member adjacent end, and holes in said disc inregistraf tion with and to telescopically receive said studs.

3. Apparatus as set forth in claim 1, wherein said tool mounting unitcomprises a generally cylindrical body formed with a radially-projectingannular collar intermediate its ends, an axially-bored tubular portionon one side of said collar for journaled reception through the casingassembly end and impact-receiving cooperation with the impact member ofthe hammer, and a cylindric extension on the other side of said collarformed with an end-opening tool-receiving socket and adapted forjournaled cooperation with an annulus xedly supported from and in axialalignment with said casing assembly,

4. Apparatus as set forth in claim 1, wherein the impact membercomprises a stem disposable axially of the casing assembly, a discradially of and threadedly fixed to `one end of said stem for drivenassociation with a rotatable hammer clutch member, a spool-like,double-cone head concentric with and threadedly fixed to the other endof said stem for impact engagement against work-transmitting elements ofthe hammer, a

" slide tongue projecting iixedly and axially from said head, a tubularcam block on and threadedly fixed to said stem between said disc andhead, and cam faces formed on the ends of said block formember-reciprocating cooperation incident to member rotation withfollowers supported by and in radially-inward projection from saidcasing assembly.

5. Apparatus as set forth in claim 1, wherein the tool mounting unitrotating means reactive to rotation of the impact member tonguecomprises a tool mounting unit tubular portion axially aligned with andopening toward the impact member in telescoping relation over the impactmember tongue, a pair of semi-cylindrical shoes nested within andsubstantially filling the bore of said tubular portion, complementary,transverseiy-arcuate grooves axially of the juxtaposed shoe diametricfaces to define an axiallystraight, transversely-oval throat, and athroatconforming, exterior contour on the impact member tongue,

6. In a hammer of the character described having a casing assembly, animpact member power-rotatable within and reciprocable as an incident ofits rotation axially of said assembly, and a tool mounting unitjournaled in an end of said assemblyk in axial alignment' with saidimpact member to receive and transmit impacts therefrom, meansresponsive to impact member rotation for frictionally engaging andyieldably rotating said tool mounting unit, said means com.. prising atubular unit end portion aligned with and opposed to said impact member,a pair of semi-cylindrica1 shoes nested within and substantially fillingthe bore of said tubular portion, friction lagging on the shoecylindrical surfaces, complementary, transversely-arcuate groovesaxially of the juxtaposed shoe diametric surfaces to define anaxially-straight, transversely-oval throat, and an axially-straight,transversely-oval tongue projecting xedly and axially from the adjacentimpact member end for slidable, nonrotatable engagement within saidthroat.

BENJAMIN W. SNODGRASS.

REFERENCES CITED The following references are of record in the le ofthis patent:

